Field of Invention
This invention relates to the removal of finely dispersed oil and solids from water using bubbles of gas to float the oil and solids to the surface of the water where they can then be skimmed off.
The principal of using gas bubbles to remove oil and solids from water is well known and is implemented in many ways with devices utilizing dissolved gas flotation and induced gas flotation.
Some major deficiencies in all types of flotation devices can be; high energy consumption, too much water carry over with the skimmings of oil and solids and high maintenance cost. On dissolved gas flotation systems the energy is used in operating the high horsepower pumps that are necessary to elevate the water pressure to the 3-4 atmospheres of pressure necessary to dissolve the gas into the water and electrical energy is used by the motors turning the wiper arms that skim the water surface. Both of these mechanisms require considerable maintenance.
Most of the induced gas flotation machines utilize high speed impellers to draw gas into contact with the water, there are usually four or five 5 HP. to 30 HP. motors used on each unit; furthermore, on most induced gas flotation machines there are incorporated motor driven, continuous rotation, skimming paddles.
Inherent to the operation of both the aforementioned type of flotation devices is the constant overflow of 5% to 15% of the processed water volume with the skimmings to disposal, this water must then be collected in tanks or sumps and pumped with pumps, consuming additional energy, back to the process stream. The mechanical complexity and high maintenance requirement of all of the above is apparent.